The primary purpose of this project is to cyclically maintain 5 filarial parasites by alternate passage through vertebrate and invertebrate hosts and supply limited amounts of these research materials to investigators. These filarial systems are as follows; 1) Brugia pahangi in jirds, dogs, cats, and Aedes aegypti (Liverpool strain) mosquitoes; 2) B. malayi in jirds, cats, and A. aegypti; 3) Litomosoides carinii in jirds, cotton rats, and Ornithonyssus bacoti mites, 4) Dipetalonema viteae in jirds, hamsters, and Ornithodoros tartakovsky ticks; and 5) Dirofilaria immitis in dogs and A. aegypti.